1. Field of the Invention
The present invention relates to a light emitting device usable for indicators, lighting apparatuses, displays, backlight of liquid crystal displays, and the like, and a method of manufacturing the same.
2. Discussion of the Related Art
In recent years, various electronic components have been proposed and are put in practical use, and increasingly high performance has been required on such components. In particular, electric components are required for maintaining performance for a long period of time even under severe environment. Light emitting devices employing a semiconductor light emitting element such as a light emitting diode (LED) are no exception to such requirements. That is, requirements for higher performance in the area of general lighting, in-vehicle lighting, and the like, is growing daily, and higher output (higher luminance) and higher reliability have been demanded. A further demand is to supply such a device at a low price while fulfilling those requirements.
In general, a light emitting device includes a support member for mounting various electronic components such as a semiconductor light emitting element (hereinafter may be referred simply as “light emitting element”) and a protective element to prevent damage on the semiconductor light emitting element caused by static electricity, and electrically conductive wirings for supplying electric power to those electronic components. In addition to those components described above, a sealing member to protect such electronic components from external environment may also be included.
In order to enhance the light extracting efficiency and to obtain a light emitting device of higher output power, it is important for such light emitting devices to reduce the absorption loss of light due to the materials of the support member, the conductive wirings, and sealing member etc.
Thus, for example, as described in JP 2007-281260A and JP 2004-055632A, a light-reflective resin layer may be arranged on the surface of the support member to reduce the absorption loss of light from the light emitting element and also to improve the light extracting efficiency.
Also, as described for example in JP 2011-514688A, in the case of a light emitting element which is mounted on a support member with a pair of positive and negative electrodes disposed on a same surface side of the light emitting element being connected to respective electrically conductive wirings with an electrically conductive member, in other words, in the case of so-called face-down mounted light emitting element, a space formed between the light emitting element and the support member may be filled with an underfill material, to prevent leakage of light from the underside of the light emitting element and thus to improve the light extracting efficiency.
However, as described in JP 2011-514688A, due to its small surface tension, an underfill material tends to cover the side surfaces of the light emitting element when the underfill material is applied to fill the space formed between the light emitting element and the support member. As a result, light emitted from the side surfaces of the light emitting element is reflected by the underfill material which covers the side surfaces of the light emitting element and returned into the light emitting element. Further, the return light may be absorbed by the electrodes or the like, which may result in a decrease in the light extracting efficiency of the light emitting device.
Also, in the case where the underfill material is applied to fill the space formed under the light emitting element which is mounted in a face-down manner, the dispenser is generally placed as close as to a side surface of the light emitting element to supply the underfill material from the dispenser. At this time, a part of the underfill material may come in touch with the side surface of the light emitting element which may result in covering the side surface. Thus, covering the side surfaces of the light emitting element with the underfill material would result in a decrease in the light extracting efficiency of the light emitting device.
In addition, the sizes of the space formed between the face-down mounted light emitting element and the support member are rather small due to existence of a plural kinds of electrically conductive members between those, which require a very small amount of the underfill material to be supplied to fill the space. Thus, in view of the workability in the coating step of applying the underfill material, application of an appropriate amount of the underfill which does not cover the side surfaces of the light emitting element is practically difficult to perform.
The present invention is devised to solve the above-described problems, and an object of the present invention is to provide an underfill material in the space between the light emitting element and the support member without covering the side surfaces of the light emitting element.